Wiki Says MCPA is deemable as environmentally hazardous herbide and has residue left in soil which typically has a half-life of 24 days
So 96 Days after MCPA use is still an active herbicide and is toxic to mammal and aquatic organisms, it can result in compromised water quality and breaches of legislative standards.
Home Use of MCPA? 
What we have found that Home users have also been using MCPA, although toxicity is still significant with a mortality of 4.4%. In Ireland, high concentrations of MCPA have been detected in many drinking water sources. MCPA can persist in water for extended periods, with reported half-lives ranging from a few days to several weeks.
Presently there are 43 MCPA products available for sale in Ireland.
To get an idea of just how deadly MCPA is, if you pealed the cover off a bottle containing MCPA and it got rinsed into a drain, the few wee drops of MCPA would Poison our water source beyond EU limits for over 30km. Products containing MCPA are available in all local hardware, animal feed and gardening shops. IS THE PRISTINE LAWN WORTH IT? . . . WE DON"T NEED TO SPREAD POISON
Farm use of MCPA
We understand that farmers use of MCPA is oftern REQUIRED to combat some weed problems, so we have more information can be found on this page. While careful use of MCPA can be understood, it should be noted that if 1 Drop of MCPA got rinsed into a drain, it would bring all the water it passed through to toxicity above EU Safe Levels for 30 KM!
Stranooden Research Project
Stranooden GWS was selected to pilot the surface water aspect of a MCPA project. As part of Phase I of the project, each GWS throughout the country that abstracts water from a lake source had their lake catchments delineated. A lake catchment simply means the area of land that drains into a river and its tributaries which then flows into a lake.
As part their role, Monaghan Co. Co. take a number of water samples each year from the Stranooden GWS’s treated drinking water network.
During this testing, MCPA was detected in certain water samples taken in 2017 and 2018. MCPA is a selective herbicide, commonly used in Ireland as a rush killer, but is also found in domestic herbicide products. Since March 2018, Stranooden GWS have carried out weekly sampling on the numerous streams and rivers that flow into White Lough to try and determine which parts of the catchment may be contributing mostly towards the problem.
